Abstract/Summary

Abstract
The established protocol for the cryopreservation of winter-dormant Malus buds requires
that stem explants, containing a single, dormant bud are desiccated at -4°C, for up to 14 days,
to reduce their water content to 25-30% of fresh weight. Using three apple cultivars, with
known differences in response to cryopreservation, the pattern of evaporative water loss has
been characterised, including early freezing events in the bud and cortical tissues that allow
further desiccation by water migration to extracellular ice. There were no significant
differences between cultivars in this respect or in the proportions of tissue water lost during
the desiccation process. Differential Scanning Calorimetry (to -90°C) of intact buds indicated
that bud tissues of the cultivar with the poorest response to cryopreservation had the highest
residual water content at the end of the desiccation process and froze at the highest
temperature
Keywords: Malus, cryopreservation, dormant bud, dehydration